Mark Twain was our first great political wit and a dogged defender of racial equality. Jon Stewart, Barack Obama and the rest of America are in his debt

Twain, pictured here in December 1908, was the first U.S. writer to achieve the kind of fame normally reserved for Presidents and generals.

In the 1880s the british poet and culture critic Matthew Arnold paid two visits to the U.S. to observe the native customs. Eventually he set down his impressions in a book, Civilization in the United States. On the whole, he didn't think there was much. For one thing, he was troubled by the way Americans appeared to lack any capacity for reverence toward superior men. "If there be a discipline in which the Americans are wanting," he pronounced, "it is the discipline of awe and respect." And in that connection, one institution of American life struck him as an especially bad...